qn.r>% 


Properly  of  the  United  States 


DEPOSITORY 


U.S.  DEPARTMENT  OF  AGRICULTURE, 

i;i  READ  OF  PLANT  [NDUSTRY— Circular  NTo.  9. 
B.  T,  Q  U.l.i  >\\  A.Y,  Chief  of  Bureau. 


TEXAS  ROOT-ROT  OF  COTTON 

FIELD  EXPERIMENTS  IN  L90T. 


By 


C.  L.  SHEAR,  Pathologist, 

\NI> 

GE(  )i;».l'   F.   MILKS.  Scientifk    Assistant. 


i  ■!•■ !l— 08 


WASHINGTON  :  GOVERNMENT  PRINTING  OFFICE  :  1008. 


BUREAU  OF  PLANT  INDUSTRY. 

Physiologist  and   Pathologist,  and   Clue)  o)    Bureau,   Beverlj    T.   Gallov 
Physiologist  and  Pathologist,  and    Assistant  Chief  of  Bureau,  Albert    1'    Woods. 

atory  of  Plant  Pathology,  Erwin   I".  Smith.  Pathologist  in  Ch 
Investigations  of  Diseases  of  Fruits,  Merton  1'..  Waite,  Pathologist   in  Charge. 
Laboratory  of  Forest  Pathology,  Haven  Metcalf,  Pathologist  in  Charge. 
Cotton  and  Truck  Diseases   <  ml  Plant   />/-.< » r v <    Survey,  William  A.  Orton,   Pathologist    in 

Charge. 
Plant  Life  History  Investigations,  Walter  T.  Swingle,  Physiologist  in  Charge. 
Cotton  Breeding  Investigations,  Archibald  I».  Shamel  and  Daniel  X.  Shoemaker,  n 

gists  in  Charge. 
Tobacco    Investigations,    Archibald    1  >.    Shamel,    Wightman    W.    Garner,    ami    Ernest    II. 

Mathewson,   in  Charge. 
Com   Investigations,  Charles   I'.    Hartley.    Physiologist    in   Charge. 
Alkali  mill  Drought  Resistant  Plant   Breeding  Investigations,  Thomas  n.  Kearney,   Physi 

oio^is!   in  Charge. 
Soil  Bacteriology  and   Water  Purification  Investigations,  Kail   I'.   Kellerman,  Physiologist 

in  Charge 
Bionomic  Im^cstigations   of   Tropical  and  Subtropical  Plants,  Orator   1'.   Cook,   Bionomist 

in  Charge. 
Drug   mill   Poisonous   Plant    Investigations   and    Tea    Cultun     Investigations,    Rodney    II. 

True,  Physiologist  in  Charge 
Physical  Laboratory,  Lyman  .1.   Briggs,   Physicist   in  Charge. 
Crop   Technology  and  Fiber  Plant   Investigations,  Nathan  A.  Cobb,   i  rop  Technologist   in 

Charge. 
Taxonomic  ami  Range  Investigations,  Frederick  V.  Coville,  Botanist  in  Charge. 
Farm    Management  Investigations,  William  J.  Spillman,  Agriculturist  in  Charge. 
Grain    Investigations,  Mark  Alfred  Carleton,  Cerealist  in   Charge. 
Arlington  Experimental  Farm,  Lee  C.  Corbett,  Horticulturist  in  Cha 
Vegetabh   Testing  Gardens,  William  W.  Tracy,  sr.,  Superintendent. 
Sugar-Beet  Investigations,  Charles  <>.  Townsend,  Pathologisl   in  Charge 
Western    Agricultural  Extension   Investigations,  Carl  S.  Scofleld,    Agriculturist  in  Charge. 
Dry  I. mni  Ail.- imiliii,  i    Investigations,  E.  Channing  Chilcott,  Agriculturist  in  Charge. 
Pomoloi/irni  colli  i  lions,  Cnstavns  P..   [Srackett,  Pomologist  in  Charge. 
Field  Investigations  in  Pomology,  William  A.  Taylor  and  G.  Harold  Powell,   Pomologists 

in  Charge. 
Experimental  Gardens  and  Grounds,  Edward   M.   Byrnes,  Superintendent. 
Foreign  Seed  ami  Plant   Introduction,  David   Fairchjld,  Agricultural    Explorer   in  Charge. 
Forage  Crop  Investigations,  Charles  V.  riper.  Agrostologist  in  Charge. 
Seed  Laboratory,  Edgar  Brown,  Botanist   in  Ch 

Grain  Standardisation,  John  D.  Shanahan,  Crop  Technologist   in  Charge. 
Subtropical  Laboratory  and  Garden,   Miami,  Fla.,  Ernst  A.  Bessey,  Pathologist  in  I 
Plant  Introduction  Garden,  Chico,  Cal.,  August   Mayer,  Expert  in  Charge. 
South   Texas  Garden,  Broivnsville,  Tex.,  Edward  C.  Green,   Pomologist   in  Charge, 
Farmers'  Cooperative  Demonstration   Work,  Seaman  A.   Knapp,  Special  Agent   in  Charge. 
Seed   Distribution    (Directed   by   Chief  of   Bureau),    Lisle   Morrison.   Assistant    in   General 

Charge. 


Edit oi .  J.  E.  Rockwell. 

cl,ii  f  <  7i  /  /.-,   James    E.   Jones. 


[Cir.  9] 


II    I'    I       37S 

TEXAS  ROOT-ROT  OF  COTTON 

FIELD  EXPERIMENTS  IN  L907. 


INTRODUCTION. 

[nvestigations  have  been  carried  oh  for  a  number  of  years  hy  the 
Bureau  of  Plant  [ndustry  in  determine  the  cause  and  the  best  methods 
nf  controlling  the  cotton  root-rot.  A  brief  account  of  the  field  work 
of  1906,  announcing  the  very  promising  results  which  were  obtained 
by  i Ice 1 1  fall  plowing  and  rotation  of  crops,  has  been  published.6  Dur- 
ing the  past  season  ii  I  periments  were  continued  along  the  same 
line  in  order  to  verify,  if  possible,  the  previous  results. 

The  results  of  the  past  two  seasons  have  been  so  satisfactory  that 
it  is  believed  thai  the  method  is  practicable  and  worthy  of  general 
adoption  in  combating  the  root-rot  of  cotton  and  also  that  of  other 
annual  or  short-lived  perennial  crop-  which  are  attacked  by  this 
disease. 

CAUSE  OF  ROOT-ROT. 

The  cause  of  this  disease,  a-  has  been  pointed  out  in  previous  publi- 
cations, i-  a  fungus,  < >:<>ii'hiiii  omnii'orum  Shear.'  which  infests  the 
>oil  and  destroys  the  roots  of  the  plant. 

REPRODUCTION   AND  DISTRIBUTION   OF   THE   FUNGUS. 

The  fungus  can  he  readily  reproduced  from  -mall  hit-  of  the 
mycelium  or   vegetative   portion   of  the   plant.     Such    pieces  of  the 


This  reporl  of  the  results  of  the  pasl  season's  field  experiments  in  the  pre 
vention  of  cotton  rool  rot  bj  Doctor  Shear  ami  .Mr.  Miles  corroborates  in  greal 
pari  I  he  very  satisfactory  results  of  the  previous  season  and  justifies  a  thorough 

trial  "I'  the  s| ifled  plan  by  planters  who  are  suffering  less  from  this  disease. 

As  [minted  em  here,  climatic  conditions  and  ether  factors  are  always  likelj   to 
cause  degree   of    variation    in    the    results   nf    this    treatment.     Further 

efforts   are   being    made    in   determine,    it'   possible,    what    modifications   nf   this 

method,    if  any.   may    increase    iis   efficiency.     A.    I'.    \V< s.    Physiologist   and 

Pathologist,  and    icting  Chief  of  Bureau. 

I'll.'  Control  "i'  Texas   Rool  Rot    "i    Cotton,   by  <'.   1..   Shear  and   George   1'. 
Miles.  Bui.  102,  pt.  •">.  Bureau  of  Plant  Industry,  1JK)7. 
■'  Bui.  Torrey  Botanical  Club,  vol.  34,  p.  305,  1JK)7. 

[Clr 

3 


4  TEXAS  ROOT-ROT  OF  COTTON. 

fungus  are  probably  distributed  by  the  wind  when  soil  containing 
the  organism  is  blown  from  one  place  to  another.  The  fungus  may 
also  undoubtedly  be  distributed  by  infected  soil  adhering  to  tools  and 
to  the  feet  of  animals. 

Since  the  disease  may  be  carried  in  the  soil,  the  practice  which  we 
arc  informed  has  been  recommended  in  Texas  of  distributing  the 
nitrogen-gathering  organisms  of  alfalfa  roots  by  the  use  of  soil  from 
old  alfalfa  fields  is  exceedingly  dangerous  and  almost  certain  to  lead 
to  the  further  dissemination  of  this  serious  disease,  which  so  far  a> 
known  at  present  is  restricted  to  southern  Oklahoma,  Texas.  New 
Mexico,  and  Arizona.  Since  alfalfa  is  affected  by  the  same  root-rot 
as  cotton  and  many  alfalfa  fields  in  Texas  are  known  to  be  badly 
infected  with  the  fungus  causing  the  disease,  every  effort  should  be 
made  to  prevent  the  distribution  of  soil  from  alfalfa  fields  in  that 
region,  and  no  person  should  purchase  or  use  such  soil,  particularly 
in  localities  or  States  where  the  root-rot  fungus  does  not  already 
occur. 

The  root-rot  is  also  suspected  on  strong  circumstantial  evidence  of 
having  one  or  two  spore  forms  by  which  it  may  be  reproduced  and 
distributed.  These  spores  may  be  easily  transported  long  distances 
by  the  wind,  and  perhaps  by  water  also.  More  work  bearing  on  the 
spore  production  of  this  fungus  is  necessary,  however,  in  order  to 
prove  the  connection  between  the  forms  suspected  and  the  root-rot 
organism. 

METHODS   OF  CONTROL. 
ROTATION    OF    CROPS. 

In  order  to  determine  experimentally  the  efficiency  of  rotation  of 
crops  in  controlling  this  disease,  an  area  of  aboul  20  acres  >>f  very 
badly  infected  black  waxy  land  was  selected  at  Terrell.  Tex.  This 
land  had  been  planted  to  cotton  for  several  seasons  and  in  1903  about 
95  per  cent  of  the  cotton  died  from  root-rot.  In  the  fall  of  1  DOT  this 
field  was  planted  to  winter  wheat.  A  good  stand  was  obtained  and 
the  wheat  grew  about  4  inches  during  the  fall.  The  winter  being 
very  severe,  however,  the  wheat  was  mostly  killed,  and  in  the  spring 
of  L905  the  land  was  plowed  -hallow  and  planted  with  corn.  Fol- 
lowing the  corn  the  land  was  plowed  2  to  -I  inches  deep  and  drilled 
to  wheat.  In  1906,  after  the  wheat  was  harvested,  a  portion  of  'he 
field  was  plowed  and  planted  to  sorghum  and  the  remainder  of  the 
held  plowed,  hut  lefi  without  a  crop  for  the  remainder  of  the  season. 
In  the  winter  of  L906-7  this  field  was  bedded  and  in  the  spring  of 
L907  it  was  planted  in  cotton,  producing  one  of  the  besl  crops  in  the 
vicinity.  There  were  only  a  very  lew  small  spot-  in  the  held  upon 
which  the  cotton  was  affected  by  the  disease,  whereas  at  the  begin 
mini:  of  the  rotation  about  !).">  per  cent  of  the  crop  was  killed  by 
root-rot. 
I  fii-.  :>\ 


I  I  \  \>    ROOT  ROT  OJ     '  0  M  ON. 
\ri:\un\    hi     I  ill:   SOIL   r.1    DEEP    FALL    PLOWING. 

A-  \v;i-  pointed  out  in  our  previous  report,  one  of  the  inosl  im- 
portant factors  in  the  development  of  this  disease  is  the  condition  of 
the  soil  in  regard  to  its  aeration.  The  heavy  black  clay  soils,  being 
very  poorh  aerated,  furnish  favorable  conditions  fur  the  develop- 
ment of  the  root-rot  fungus  and  at  the  same  time  are  very  unfavor- 
able for  the  most  healthy  development  of  the  rool  system  of  the  cot- 
ton plant,  and  any  practice  which  will  loosen  this  soil  and  improve  its 
physical  condition  so  that  more  air  will  reach  the  roots  of  the  plants 
appears  greath  to  Lessen  the  injury  from  tin-,  disease.  On  November 
12,  1906,  a  field  at  Petty,  Tex.,  upon  which  most  of  the  cotton  for  sev- 
eral years  had  died  with  mot -ml.  was  plowed  7  to  9  inches  deep  with 
•I  LO-inch  plow.  In  the  spring  of  L907  the  land  was  bedded  and 
planted  to  cotton.  Owing  to  unfavorable  weather  conditions  the 
cotton  had  to  be  replanted  twice,  the  final  planting  being  done  on 
May  L8.  A  portion  of  the  same  held  was  also  plowed  .-hallow  in  the 
ordinary  manner  in  the  spring  of  L907  and  used  as  a  check  plat  to 
compare  with  the  plat  which  was  deep  fall  plowed. 

The  cotton  on  both  plats  was  given  ordinary  cultivation  during 
the  season.  <  )n  November  11.  L907,  all  the  living  and  dead  plants 
on  both  plats  were  counted.  On  the  plat  which  had  received  the 
deep  fall  plowing  only  26.79  per  cent  of  the  plants  were  death  and 
most  of  these  plant-  had  matured  their  crop  before  dying.  On  the 
adjoining  plat  which  had  received  ordinary  spring  tillage  69.5J 
per  cent  of  the  plant-  were  dead  from  the  disease,  and  most  of  these 
plants  had  died  SO  early  that  they  produced  but  little  cotton.  The 
accompanying  reproduction  of  a  photograph  of  these  plats  .-hows 
their  appearance  al    the  lime  the  count-   were   made.      (Fig.    1.) 

At  the  same  time  another  Held  in  the  same  vicinity,  also  very  badly 
infected  with  root-rot,  was  plowed  7  to  9  inches  deep  with  a  1  1-inch 
riding  plow.  The  plat  was  planted  in  the  spring,  and  at  the  same 
time  an  adjoining  plat  was  given  ordinary  tillage  and  planted  as  a 
check.  Both  plats  received  the  same  cultivation  during  the  season. 
On  November  11.  L907,  the  plat  which  received  the  deep  fall  plow- 
ing showed  by  adnal  count  of  all  the  plant-  only  1  l.s7  per  cent  dead. 
and  on  these  most  of  the  crop  had  matured  before  their  death.  On 
the  check  plat  which  received  ordinary  spring  tillage  .">7.v7  per  cent 
of  the  plants  were  killed  by  the  disease,  and  these  plant-  died  so 
early  that  they  did  not  mature  nearly  so  mam  bolls  a-  those  on  the 
deep-plowed   plat. 

These  results  are  not  quite  so  satisfactory  as  those  obtained  in  L906, 
but  are  quite  sufficient  to  justify  and  make  profitable  this  method  of 
treatment.  The  benefit  derived  from  thi-  treatment  necessarily  de- 
pend- in  -nine  extent    upon   various   factors  which  arc  more  or  less 

[Clr.  '.'I 


6 


TEXAS  ROOT-ROT  OF  COTTON. 


uncontrollable.  The  most  important  of  these  are  the  condition  of  the 
soil  at  the  time  the  plowing  is  done  and  the  climatic  condition-  which 
prevail  during  the  succeeding  winter,  as  these  factors  will  greatly 
affeel  the  amount  of  disintegration  and  aeration  which  will  take  place 
in  the  soil  during  the  winter.  The  plowing,  of  course,  should  be  done 
only  when  the  soil  is  in  proper  condition — neither  too  wet  nor  too  dry. 

SUMMARY. 

Rotation  with  immune  crops  at  Terrell.  Tex.,  resulted  as  follow-: 
1904.  planted  to  cotton,  about  95  per  cent  of  which  was  killed  by 
root-rot. 


Fig.  1. — Experimental  plats  of  cotton  at  Petty,  Tex.,  showing  the  results  of  (loop  fall  plow- 
ing. Plat  A,  at  the  left,  was  plowed  7  to  0  inches  deep  "ti  November  12,  1906.  Only 
26.79  per  cent  of  these  plants  were  dead  on  November  11,  1907,  and  most  of  these  had 
matured  their  crop.  Plat  B,  at  the  right,  received  ordinary  spring  plowing.  Of  these 
plants,  69.54  per  cent  were  dead  on  November  11,  1907,  and  these  had  died  so  early 
that  they  matured  bu1  a  small  part  of  their  crop. 

L905,  planted  to  coin. 

1900.  planted  to  wheat,  followed  by  sorghum  the  same  season. 

1907.  cotton  again  planted,  with  the  result  that  as  nearly  as  could 
be  estimated  less  than  5  per  cent  of  the  cotton  was  dead  at  the  close 
of  the  season. 

Land  badly  infected  with  root-rot  was  plowed  7  to  !•  inches  deep 
November  11.  1906,  at  Petty.  Tex.  In  experiment  No.  1  the  deep- 
plowed  plat  showed  1:2.75  per  cent  Less  dead  plant-  than  the  adjoining 
check  plat  which  received  the  customary  tillage.  In  experiment  No. 
■2  the  deep-plowed  plat  showed  43  per  cent  le>s  dead  plants  than  the 
[Cir.  !)J 


TEX  V.S    Ri  '< '  i    R(  1 1'   OF    COT  rON.  , 

adjoining  check  plat,  and  in  both  cases  a  much  larger  amounl  of 
cotton  was  produced  on  the  dead  plants  on  the  treated  plats,  because 
these  plants  did  not  die  until  later  than  those  on  the  untreated  plats. 
and  therefore  had  greater  opportunity  to  mature  their  liolls. 

CONCLUSIONS. 

A  combination  of  rotation  of  crops  and  deep  fall  plowing  will 
probabl}'  be  found  the  most  satisfactory,  efficient,  and  practicable 
means  of  controlling  the  root  rot  of  cotton.  In  combination  with  a 
short  rotation  the  deep  fall  plowing  would  perhaps  be  needed  only 
i  \  i  i  ■  \   ot  her  year. 

Experience  indicates  that  better  tillage  and  rotation  of  crops  in 
any  case  must  be  more  generally  practiced  in  the  future  by  cotton 
planters  i  I'  profitable  crops  are  to  be  produced,  even  in  localities  where 
the  root  -rot  is  not  present. 

Approved : 

J  \  siES  Wilson, 

v  i  n  tin  ij  of  .  Agriculture. 

Washington,  i>.  c.  May  u,  wos. 

9] 

O 


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3  1262  08929  0018 


